Effect of different doses of transdermal fentanyl on the reproductive system in male rats

Fentanyl, a potent synthetic opioid analgesic, is commonly used to manage severe pain. However, the effects of fentanyl use on male reproductive health have not been adequately studied. This study aimed to investigate the effects of different doses of transdermal fentanyl patches on various reproductive parameters in male rats. Adult male Albino Wistar rats were divided into four groups. The treatment groups received transdermal fentanyl at doses of 25 mcg/h (Group II), 50 mcg/h (Group III), and 100 mcg/h (Group IV) for 9 days, respectively. Sperm motility, sperm concentration, abnormal sperm, live/dead sperm, testicular apoptosis, testicular oxidative stress, and androgen receptor levels were evaluated. The results showed that fentanyl administration decreased the oxidative stress parameters CAT and SOD1 levels in all treatment groups (p<0.001). No significant changes were observed in sperm motility, abnormal sperm ratio, or live/dead sperm ratio. However, Group IV showed a significant increase in sperm concentration compared to the other groups (p<0.001). In addition, all fentanyl treatment groups showed a significant increase in apoptosis-related Caspase 3/8/9 enzymes (p<0.001). This study reveals the effects of fentanyl on male reproductive health. This is the first study to demonstrate an increase in sperm concentration associated with high fentanyl doses.